Southern Cross Medical Library

Parkinson's disease - symptoms, causes, treatment

Parkinson’s disease is a progressive, degenerative disorder of the brain; symptoms include tremors, stiffness and rigidity, and slowness of movement (bradykinesia).

According to Parkinson’s New Zealand, approximately 1% of people over the age of 60 have the condition. Various theories exist regarding causes of the disease. There is no cure for Parkinson’s disease so treatment will normally focus on managing symptoms, typically with medication.

Signs and symptoms

The distinction symptoms of Parkinson’s disease include:

Tremor

Most people with Parkinson’s disease develop a tremor that is most prominent in the hands and fingers. It tends to occur when the limb is relaxed (a resting tremor), disappearing when performing tasks such as drinking or eating. About 30% of people with Parkinson’s disease never develop a tremor.

Stiffness

This is a common early sign of Parkinson’s disease and is most obvious in the arms, shoulder or neck, although it can occur in all muscle groups. People may have difficulty getting out of a chair, turning or rolling over in bed, or walking. Fine finger movements such as doing up a button or tying a shoelace may also be difficult. Pain or a deep aching sensation in the muscles may also be felt.

Bradykinesia

This means slowness of movement and is a disabling and frustrating symptom of Parkinson’s disease. People have difficulty initiating movement and movement may be slow. There may also be a lack of coordination when moving and normal activities can prove difficult. Activities once performed quickly and comfortably, such as washing or dressing, may take several hours if not assisted. Bradykinesia can also make the face seem flat or expressionless.

Loss of Balance

This is a symptom that tends to develop later in Parkinson’s disease. Because of impaired balance and co-ordination (postural instability) a person with Parkinson’s disease can develop a forward or backward lean. They may start to walk with small steps as if hurrying forward to keep balance (festinations). Frequent falls are also common.

Causes

Parkinson’s disease occurs as the result of insufficient quantities of the neurotransmitter dopamine in a part of the brain called the substantia nigra. The substantia nigra helps in the planning and programming of movement. A neurotransmitter is a chemical substance that is released from the ends of neurones (nerve cells) to communicate with one or several other neurones. Dopamine levels are reduced as the neurones that produce dopamine die. As a result, messages concerning the planning and programming of movement are interrupted.

It is not known why this occurs but several possible causes have been studied:

Genetic factors

In approximately 15% of Parkinson’s patients there is a family history. It is not known if this is due to a shared, defective gene, environmental factors, or both. A defective gene has been identified in a rare, early-onset form of Parkinson’s disease.

Environmental toxins

Despite no conclusive evidence that this is a cause, some scientists believe that an internal or external toxin affects the body’s ability to produce dopamine.

Accelerated ageing

One theory is that in some individuals, for some unknown reason, the normal, age-related death of the neurones that produce dopamine is accelerated

Free Radicals

Some researchers believe that the neurones that produce dopamine die due to the activity of free radicals. Free radicals are potentially damaging molecules produced in the body during normal chemical reactions.

Apparent risk factors for developing Parkinson’s disease include:

Age

Male gender

Family history of Parkinson’s

Extreme stress

Head trauma

Caucasian ancestry

Herbicide/pesticide exposure

Rural residence

Higher intake of dietary fats

Several factors have also been associated with a decreased risk and include:

Diagnosis

There is a no single test to diagnose Parkinson’s disease. In its early stages a diagnosis of Parkinson’s disease can be very difficult even for an experienced doctor. If Parkinson’s disease is suspected, a referral to a neurologist (nervous system specialist) may be recommended. The neurologist may need to observe the person for some time as Parkinson’s disease does not usually occur suddenly. Approximately 80% of cells within the substantia nigra need to die before symptoms are apparent.

A diagnosis is based on:

A person’s medical history

Observing symptoms

A neurological and physical examination – this may involve the use of imaging techniques such as computerised tomography (CT) or magnetic resonance imaging (MRI) to rule out other conditions.

Treatment

Parkinson’s disease cannot be cured so treatment focuses on managing symptoms. Several treatments are used in the management of Parkinson’s disease. These include:

Medications

Medications can provide dramatic results and there are a number that can be prescribed. The two mediations most commonly used to help control symptoms are:

Levodopa: This drug has proven to be an effective treatment for many people. Levodopa is converted to dopamine within the brain, reducing many of the disabling symptoms of Parkinson’s disease. Over time the effect of levodopa can decrease and it can also cause unwanted side effects. For this reason it may be avoided in the early stages of the condition.

Dopamine agonists: Whereas levodopa artificially replaces dopamine in the brain, dopamine agonists mimic the effects of the lost dopamine. They can be used alone or in combination with levodopa. Dopamine agonists can remain effective for several years and avoid some of the unwanted side-effects of levodopa.

Physiotherapy

Mobility, co-ordination, range of motion and muscle tone can all be improved with physiotherapy. Increasing muscle strength and improving gait and balance also helps prevent falls allowing the person with Parkinson’s disease to feel more confident and capable.

Brain surgery

Surgery, while not commonly performed, may be appropriate in cases of very severe tremor or dyskinesia (involuntary movements) that cannot be adequately controlled with medication. This is done by a specialist neurosurgeon. In recent years deep brain stimulation (DBS) has become the main surgical option for Parkinson's disease. It involves implanting a small electrode into a specific area of the brain. The implanted electrode, controlled by a pacemaker-like device implanted under the skin below the collar bone, generates electrical currents that disrupt signals from the brain that cause tremors. The surgery is major and can take over eight hours. DBS is not a cure and the crtieria for selection of patients appropriate for the surgery are very strict.

Self-help measures

A range of self-help strategies can help improve the quality of life of a person with Parkinson’s disease. These include:

Exercise

Movement is affected in Parkinson’s disease and exercise can improve mobility and general health. The response of the body to dopamine also seems to improve with exercise. Parkinsons New Zealand suggests that people with the disease aim to get at least 20-30 minutes each day of aerobic exercise, such as walking.

Sleep

Sleep is important to Parkinson’s disease sufferers. Most people with the disease tend to feel better in the morning and deteriorate during the day. Many also find that having a good day is related to having had a good night’s sleep. In addition the brain recharges its dopamine overnight.

Diet

It is important to eat a nutritionally balanced diet. However, no specific diet has been shown to be of therapeutic value in Parkinson’s disease.

Alternative treatments

Treatments such as massage, acupuncture and yoga have proved helpful in relieving symptoms in some people. Vitamin, mineral and herbal remedies may also prove beneficial in some cases.

It is important to discuss the use of any alternative therapies with the doctor, as some of these therapies may interact with conventional treatments.

Parkinson's New Zealand (2013) The Drug Treatment of Parkinson’s: A Guide for People with Parkinson's and Those Who Care for Them (PDF).Wellington. www.parkinsons.org.nz/sites/default/files/page/Publications/Parkinson%27s_Drug_Book_WEB.pdf